Apparatus for and method of treating and cooling cement clinker

ABSTRACT

This invention relates to an apparatus for and method of cooling and treating cement clinker discharged from a discharge end of a cement kiln, which kiln has a burner disposed adjacent the discharge end. The apparatus has a grate-type cooling means adapted to receive a bed of the cement clinker from the discharge end at a temperature of about 2,700to 2,800* F. and to discharge the cement clinker at a temperature of about 350* F. The cooling means has a pressure zone for cooling the cement clinker from a temperature of about 2,500* to a temperature of about 1,850*. A first cooling means is disposed adjacent the pressure zone for directing a pressurized cooling fluid through the cooling means and through the bed to cool the cement clinker from a temperature of about 2,500* F. to a temperature of about 1,850* F. and also to heat the cooling fluid to a temperature of about 400* to about 500* F. for use as secondary air for the burner. The cooling means also has a reduction and cooling zone adjacent the pressure zone for cooling and treating the cement clinker from a temperature of about 1,850* F. to a temperature of about 1,100* F. Gas generator means in the reduction and cooling zone direct a pressurized reducing fluid through the cooling means and through the bed to cool the cement clinker from a temperature of about 1,850* F. to a temperature of about 1,100* F. and to exit the reducing fluid from the reduction and cooling zone. Additionally, the cooling means has a cooling zone adjacent the reduction and cooling zone for cooling the cement clinker from a temperature of about 1,100* F. to a temperature of about 350* F. A second cooling means adjacent the cooling zone directs a pressurized cooling fluid through the cooling means and through the bed to cool the cement clinker from about 1,100* F. to about 350* F. and to heat the cooling fluid to a temperature of about 230* to 250* F. for use as primary air for the burner. The method includes the steps of receiving a bed of the cement clinker on a grate-type cooling means from the discharge end at a temperature of about 2,700* to 2,800* F.; cooling the cement clinker in a pressure zone of the cooling means from a temperature of about 2,500* F. to a temperature of about 1,850* F. by directing a pressurized cooling fluid through the cooling means and through the bed to heat the cooling fluid to a temperature of about 400* to about 500* F. for use as secondary air for the burner; cooling the partially cooled cement clinker in a reduction and cooling zone adjacent the pressure zone of the cooling means from a temperature of about 1,850* F. to a temperature of about 1,100* F. by directing a pressurized reducing fluid through the cooling means and through the bed and to exit the reducing fluid from the reduction and cooling zone; and cooling the reduced cement clinker in a cooling zone adjacent the reduction and cooling zone from a temperature of about 1,100* F. to a temperature of about 350* F. by directing a pressurized cooling fluid through the cooling means and through the bed to heat the cooling fluid to a temperature of about 230* to 250* F. for use as primary air for the burner.

United States Patent Stewart W. l'resouthielt McClndless Township,Allegheny County.

{72] Inventor Pa. [2H Appl No L486 122] Filed Jan. 8, i970 [45] PatentedJuly 27, 197! [73] Assignee United States Steel Corporation [54]APPARATUS FOR AND METHOD OF TREATING AND COOLING CEMENT CLINKER 30Claims, I Drawing Fig.

Primary Examiner.lohn J. Camby Att0rneyRobert .l. Leek, .lr.

ABSTRACT: This invention relates to an apparatus for and method ofcooling and treating cement clinker discharged from a discharge end of acement kiln, which kiln has a burner disposed adjacent the dischargeend. The apparatus has a grate-type cooling means adapted to receive abed of the cement clinker from the discharge end at a temperature ofabout 2,700" to 2,800 F. and to discharge the cement clinker at atemperature of about 350 F. The cooling means has a pres sure zone forcooling the cement clinker from a temperature of about 2,500 to atemperature of about 1,850. A first cooling means is disposed adjacentthe pressure zone for directing a pressurized cooling flllld through thecooling means and through the bed to cool the cement clinker from atemperature of about 2,500 F to a temperature of about L850 F and alsoto heat the cooling fluid to a temperature of about 400 to about 500 F.for use as secondary air for the burner. The cooling means also has areduction and cooling zone adjacent the pressure zone for cooling andtreating the cement clinker from a temperature of about 1,850 F. to atemperature of about l,l00 F. Gas generator means in the reduction andcooling zone direct a pressurized reducing fluid through the coolingmeans and through the bed to cool the cement clinker from a temperatureof about l,850 F. to a temperature of about l,l00 F. and to exit thereducing fluid from the reduction and cooling zone. Additionally, thecooling means has a cooling zone adjacent the reduction and cooling zonefor cooling the cement clinker from a temperature of about l,l00 F. to atemperature of about 350 F. A second cooling means adjacent the coolingzone directs a pressurized cooling fluid through the cooling means andthrough the bed to cool the cement clinker from about l,l00 F. to about350 F. and to heat the cooling fluid to a temperature of about 230 to250 F. for use as primary air for the burner.

The method includes the steps of receiving a bed of the cement clinkeron a grate-type cooling means from the discharge end at a temperature ofabout 2,700 to 2,800 E; cooling the cement clinker in a pressure zone ofthe cooling means from a temperature of about 2,500" F. to a temperatureof about L850 F. by directing a pressurized cooling fluid through thecooling means and through the bed to heat the cooling fluid to atemperature of about 400 to about 500 F. for use as secondary air forthe burner; cooling the partially cooled cement clinker in a reductionand cooling zone adjacent the pressure zone of the cooling means from atemperature of about l,850 F. to a temperature of about l,l00 F. bydirecting a pressurized reducing fluid through the cooling means andthrough the bed and to exit the reducing fluid from the reduction andcooling zone; and cooling the reduced cement clinker in a cooling zoneadjacent the reduction and cooling zone from a temperature of aboutl,l00 F. to a temperature of about 350 F. by directing a pressurizedcooling fluid through the cooling means and through the bed to heat thecooling fluid to a temperature of about 230 to 250 F. for use as primaryair for the burner.

PATENTEBJULNIH?! 3,595,543

from

fuel supply INVENTOR STEWAR K. TRES THICK APPARATUS FOR AND METHOD OFTREATING AND COOLING CEMENT CLINKER BACKGROU ND OF THE INVENTIONHeretofore, in the manufacture of white cement, a suitable raw materiallow in metallic oxides, such as iron oxide, manganese oxide, chromeoxide, etc., was used and burned in a rotary kiln using conventionalmethods to either rapidly quench the resultant clinker in a neutralmedium, or to cool the clinker under reducing conditions.

Similarly. it is known in the art that water or steam quenching grayportland cement clinker, i.e., regular portland cement clinker will,within proper temperature and time limits produce a light buff clinker.Also, it is known that treating the same clinker with a chemicalreductant under proper conditions of temperature and time will produce alight buff clinker. Both types of clinkers can be manufactured into apleasing, desirable light buff-colored cement.

Conventional methods of treating the clinker require high maintenanceand/or high fuel usage. The high fuel usage results from the wasting ofall or most of the sensible heat in the clinker which is not returned tothe heat input of the kiln thus lowering to a marked degree the thermalefficiency of the pyroprocess.

OBJECTS OF THE INVENTION It is the general object of this invention toavoid and overcome the foregoing and other difficulties of andobjections to prior art practices by the provision of a method of andapparatus for cooling and treating white and gray cement clinker, whichmethod and apparatus:

1. utilize sensible heat in the clinker to recuperate a significantamount of thermal energy for reuse in the pyroprocess;

2. utilize a reducing atmosphere to cool the clinker from an uppertemperature reaction limit of about 2,000 to l,850 F. to a lowertemperature limit of about l,000 to l,l F. at which temperature theclinker will not react with oxygen in the air; and

. supplying uniformly heated primary and secondary air to the combustionprocess for a more stable combustion process leading to a more uniformkiln operation.

BRIEF SUMMARY OF THE INVENTION The aforesaid objects of this invention,and other objects which will become apparent as the description proceedsare achieved by providing an improved apparatus for and method ofcooling a cement clinker. The apparatus has a grate-type cooling meansadapted to receive a bed of the cement clinker from the discharge end ofthe kiln at a temperature of about 2,700 to about 2,800 F. and todischarge the cement clinker at a temperature of about 350 F. Thecooling means has a pressure zone for cooling the cement clinker from atemperature of about 2,500 F. to a temperature of about 1,850 F. A firstcooling means is disposed adjacent the pressure zone for directing apressurized cooling fluid through the cooling means and through the bedto cool the cement clinker from a temperature of about 2,500 F. to atemperature of about 1,850 F. and also to heat the cooling fluid to atemperature of about 400 to about 500 F. for use as secondary air forthe burner. The cooling means also has a reduction and cooling zoneadjacent the pressure zone for cooling the cement clinker from atemperature of about l,850 F. to a temperature of about 1,100 F Gasgenerator means in the reduction and cooling zone direct a pressurizedreducing fluid through the cooling means and through the bed to cool thecement clinker from a temperature of about 1,850 F. to a temperature ofabout l,l00 F. and to exit the reducing fluid from the reduction andcooling zone. Additionally, the cooling means has a cooling zoneadjacent the reduction and cooling zone for cooling the cement clinkerfrom a temperature of about l,l00 F. to a temperature of about 350 F. Asecond cooling means adjacent the cooling zone directs a pressurizedcooling fluid through the cooling means and through the bed to cool thecement clinker from about l,l00 F. to about 350 F. and to heat thecooling fluid to a temperature of about 230 to 250 F. for use as primaryair for the burner.

The method includes the steps of receiving a bed of the cement clinkeron a grate-type cooling means from the discharge end of a kiln at atemperature of about 2,700 to 2,800 E; cooling the cement clinker in apressure zone of the cooling means from a temperature of about 2,500 F.to a temperature of about 1,850 F. by directing a pressurized coolingfluid through the cooling means and through the bed to heat the coolingfluid to a temperature of about 400 to about 500 F. for use as secondaryair for the burner; cooling the partially cooled cement clinker in areduction and cooling zone adjacent the pressure zone of the coolingmeans from a temperature of about l,850 F. to a temperature of aboutl,l00 F. by directing a pressurized reducing fluid through the coolingmeans and through the bed and to exit the reducing fluid from thereduction and cooling zone; and cooling the reduced cement clinker in acooling zonc adjacent the reduction and cooling zone from a temperatureof about l,l00 F. to a temperature of about 350 F. by directing apressurized cooling fluid through the cooling means and through the bedto heat the cooling fluid to a temperature of about 230 to 250 F. foruse as primary air for the burner.

BRIEF DESCRIPTION OF THE DRAWING For a better understanding of thisinvention, reference should be had to the accompanying drawing whereinlike numerals of reference indicate similar parts throughout the sin gleview and wherein the sole figure is a diagrammatic view of the improvedapparatus of this invention for cooling cement clinker.

Although the principles of this invention are broadly applicable to thecooling of all portland cement clinker, this invention is particularlyadapted for use in conjunction with the cooling of white cement clinkerand hence it has been so illustrated and will be so described.

DETAILED DESCRIPTION With specific reference to the form of thisinvention illustrated in the drawing, an apparatus for cooling a cementclinker l0 discharged from a discharge end 12 of a cement kiln I4, isindicated generally by the reference numeral IS. The kiln 14 has aburner 16 disposed adjacent the discharge end I2.

This apparatus 18 has a grate-type cooling means, such as the grate-typecooler 20 of the type manufactured by the Fuller Company, Catasauqua,Pennsylvania and adapted to receive a bed 22 of cement clinker 10 whichdischarges from the kiln end l2 at a temperature of about 2,700 to about2,800 F. and is about 2,500 F. at the cooler. The cooler 20 dischargesthe cement clinker 10 at a temperature of about 350 F. as hereinafterexplained. The bed 22 of cement clinker I0 is disposed on the cooler 20to a predetermined depth of about 8 inches to about 20 inches.

PRESSURE ZONE Z,

The cooler 20 has a pressure zone Z, for cooling the cement clinker 10from a temperature of about 2,500 F. to a temperature of about 1,850 F.The pressure zone Z, has a first predetermined length of about 10percent to 15 percent of the total length of the cooler 20 and aretention time of about 6 to about 7 minutes. The pressure zone 2,. isdefined on one side of the cooler 20, (in this case the lower side ofthe cooler 20) by a pressure compartment 24. The other side of thepressure zone 2;, (i.e., the top side thereof above the cooler 20) isdefined by a first hanging baffle 25 and a cooler throat 30.

A first cooling means, such as the first fan 26, is disposed adjacentthe pressure zone Z, or the pressure compartment 24 and connnectedthereto by a conduit 28. Such first fan 26 directs a cooling fluid, suchas ambient air or the like, at a pressure sufficient to pass the coolingfluid through the cooler 20 and the bed 22 ofthe cement clinker It) tocool the cement clinker 10 from a temperature of about 2,500" F. to atemperature of about 1,850" F. and also to heat the cooling fluid to atemperature of about 400 to about 500 F. for use as secondary air forthe burner 16. As shown in the drawing, such secondary air is conductedby the cooler throat 30 adjacent the discharge end 12 of the kiln 14 tothe burner I6.

REDUCTION AND COOLING ZONE Z,

The cooler 20 has a reduction and cooling zone Z, adjacent the pressurezone Z, for cooling the cement clinker 10 from a temperature of about1,850 F. to a temperature of about l,l F. The reduction and cooling zoneZ, has a second predetermined length of about 25 percent30 percent ofthe total length of the cooler 20 and utilizes a retention time greaterthan about minutes. Such reduction and cooling zone Z, is defined on oneside of the cooler (i.e. the lower side) by a reduction and coolingfluid plenum chamber 32 and on the other side (i.e. the top side) of thecooler 20 by the compartment 320, first hanging baffle and the secondhanging baffle 34. For the purpose of exhausting the reducing gases, anexhaust means such as the exhaust stack 36 is provided in the reductionand cooling zone Z, or the reduction and cooling compartment 32. A gasgenerator means, such as the gas generator 38 of the type DXmanufactured by Midland-Ross Corp., Toledo, Ohio, produces a reducinggas comprising approximately 80 percent N,, l0 percent C0,, a 4 percentmixture of CO and H, and 6 percent H,O at ambient temperature. A fan 40directs such reducing fluid through a conduit 39, the cooler 20 and thebed 22 to cool the cement clinker [0 from a temperature of about l,800F. to a temperature of 1,100" F. and to exit the reducing fluid from thereduction and cooling zone Z, through the exhaust stack 36.

COOLING ZONE Z Adjacent the reduction and cooling zone Z, the cooler 20has a cooling zone Z,- for cooling the reduced cement clinker 10 from atemperature of about l,l00 F. to a temperature of about 350 F. Thecooling zone 2 has a third predetermined length of about 55 percent-6Spercent of the total length of the cooler 20, and utilizes a retentiontime of about 20 to about 30 minutes. Such cooling zone 2, is defined onthe lower side of the cooler 20 by a cooling fluid plenum chamber 42 andabove the cooler 20 by the second hanging baffle 34 and an end section44.

A second cooling means, such as the fan 46, is connected by a conduit 48to the cooling fluid plenum chamber 42 and is utilized for directing apressurized cooling fluid through the conduit 48, the cooler 20, and thebed 22 to cool the cement clinker 10 from a temperature of about l,l00F. to a temperature of about 350 F. and also to heat the cooling fluidto a temperature of about 230 to 250 F for use as primary air for theburner 16. The primary air for the burner 16 exits from the coolingcompartment by way of an exhaust stack 50. A portion of the primary airis diverted by a fan 52 through a conduit 54 extending from the exhauststack to the burner 16.

As shown in the drawing, the cooled reduced cement clinker I0 falls offthe cooler 20 onto a discharge conveyor 56.

CONTROL MEANS HOOD PRESSURE CONTROL For the purpose of maintaining aslightly negative pressure in the hood 30, such as about 0.05 inches ofawater column, a first pressure sensing means, such as the sensor 58 ofthe type 252A manufactured by The Hayes Corporation, Michigan City,Indiana, is disposed in the hood or cooler throat 30 for sensing thepressure in the hood 30. A first damper means, such as the damper 60, islocated in the conduit S4. A first control means, such as a recordercontrol 62 of the Furnace Pressure Controller type manufactured by Leedsand Northrup, Philadelphia, Pennsylvania is connected to the firstsensor 58 and to a first actuator 64 of the type RC manu factored byBailey Meter Company, Cleveland, Ohio, which first actuator 64 is inturn connected to the first damper 60.

REDUCTION AND COOLING ZONE TEMPERATURE CONTROL In order to maintain thecement clinker I0 at a temperature of about I,8S0, as the cement clinkerI0 leaves the pressure zone 2,, a second damper means, such as thesecond damper 66, is disposed in the conduit 28; a first temperaturesensing means, such as the temperature sensor 68 of the type Rayotubemanufactured by Leeds and Northrup Company is disposed in the top of thereduction and cooling compartment 32 adjacent the first baffle 25 tosense the entrance temperature of the gases to the reduction and coolingzone 2,. A second control means, such as a second recorder controller 70of the type H Speedomax manufactured by Leeds and Northrup Company,Philadelphia, Pennsylvania and a second actuator 72 of the type RCmanufactured by Bailey Meter Company, Cleveland, Ohio are connected tothe second damper 66.

REDUCING FLUID FLOW CONTROL For the purpose of controlling the flow ofthe reducing fluid through the reduction and cooling zone 2,, a thirddamper means, such as the third camper 74, is disposed in the conduit 39between the gas generator 38 and the reduction and cooling compartment32. A second temperature sensing means, such as the second temperaturesensor 76, of the type Rayotube manufactured by Leeds and Northrup,Philadelphia, Pennsylvania, is disposed in the reduction and coolingzone Z, adjacent the exit portions thereof and the second baf- He 34. Athird controller means, such as the third recorder controller 78 of thetype H Speedomax manufactured by Leeds and Northrup Company,Philadelphia, Pennsylvania, and an actuator 80 of the type RCmanufactured by Bailey Meter Company are connected respectively to thesecond temperature sensor 76 and to the third damper 74.

PRESSURE CONTROL IN PRESSURE AND COOLING ZONE In order to maintain aslightly positive pressure, such as about +0.05 inches of a watercolumn, in the reduction and cooling zone Z,, a second pressure sensor82 of the type 252A manufactured by Hayes Company, Michigan City,Indiana, is disposed in the reduction and cooling zone 2,. A fourthdamper means, such as the fourth damper B4, is disposed in the exhauststack 36 and a fourth control means, such as the fourth recordercontroller 86 of the type H Speedomax manufactured by Leeds and NorthrupCompany, Philadelphia, Pennsylvania, is connected to the second pressuresensor 82. An actuator 88 of the type RC manufactured by Bailey MeterCompany Cleveland, Ohio, is connected to the fourth recorder controller86 and to the fourth damper 84.

PRESSURE CONTROL IN COOLING ZONE To maintain a slightly negativepressure, such as about 0.05 inches of a water column, in the coolingzone Z a fifth damper means, such as the fifth damper 90 is disposed inthe exhaust stack 50. A third pressure sensing means, Type 25 2A- HayesCompany, such as the third pressure sensor 92, is inserted into thecooling zone 2, adjacent the discharge portions of the cooler 20 and isconnected to a fifth controller recorder 94 of the type H Speedomaxmanufactured by Leeds and Northrup Company, Philadelphia, Pennsylvania.The control recorder 94 in turn is connected to an actuator 96 (similarto actuator 88), which actuator 96 is connected to the fifth damper 90.

COOLING FLUID FLOW CONTROL IN COOLING ZONE For the purpose ofcontrolling the flow of cooling fluid through the cooling zone 2 a sixthdamper means, such as the sixth damper 98. is disposed in the conduit 48and is operated manually to achieve the desired flow.

ALTERNATIVE EMBODIMENTS it will be understood by those skilled in theart that alternatively the various control means shown in the solefigure of the drawing may be interchanged as desired to achieve aparticular predetermined control pattern.

METHOD It will be apparent to those skilled in the art from the abovedescription of the apparatus that an improved method of cooling a cementclinker 10 has been disclosed. The method includes the steps ofreceiving a bed 22 of the cement clinker It] on a grate-type cooler fromthe discharge end 12 of a kiln [4 at a temperature of about 2,700 to2,800 F.; cooling the cement clinker 10 in a pressure zone 2, of thecooler 20 from a temperature of about 2,500" F. to a temperature ofabout 1,850" F. by directing a pressurized cooling fluid through thecooler 20 and the bed 22 to heat the cooling fluid to a temperature ofabout 400 to about 500 F. for use as secondary air for a burner 16;cooling the partially cooled cement clinker 10 in the reduction andcooling zone Z. adjacent the pressure zone Z, of the cooler 20 from atemperature of about 1.850" F. to a temperature of about 1, I00 F. bydirecting a reducing pressurized fluid through the cooler 20 and the bed22 and to exit the reducing fluid from the reduction and cooling zone2.; and cooling the reduced cement clinker 10 in a cooling zone Z of thecooler 20 adjacent the reduction and cooling zone Z. from a temperatureof about l,l00 F. to a temperature of about 350 F. by directing apressurized cooling fluid through the cooler 20 and the bed 22 and alsoto heat the cooling fluid to a temperature of about 230 to about 250 F.for use as primary air for the burner 16.

SUMMARY OF THE ACHIEVEMENT OF THE OBJECTS OF THE lNVENTlON It will berecognized by those skilled in the art that the objects of thisinvention have been achieved by providing an improved apparatus for andmethod of cooling white cement clinker, which method and apparatusutilize sensible heat in the clinker 10 to recuperate a significantamount of thermal energy for reuse in die pyroprocess; utilize areducing atmosphere to cool the clinker 10 from an upper temperaturereaction limit of about 2,000 to about L850 F. to a lower temperaturelimit of about I000 to about l,l00 F. at which temperature the clinker10 will not react with oxygen in the air; and supplying uniformly heatedprimary and secondary air to the combustion process for a more stablecombustion process leading to a more uniform kiln operation.

While in accbrdance with the patent statutes, preferred and alternativeembodiments of this invention have been illustrated and described indetail, it is to be particularly understood that the invention is notlimited thereto or thereby.

I claim:

1. Apparatus for cooling cement clinker discharged from a dischargedfrom a discharge end of a cement kiln, said kiln having a burnerdisposed adjacent said discharge end, said apparatus having:

a. grate-type cooling means adapted to receive a bed of said cementclinker from said discharge end at a temperature of about 2,700 to about2,800" F. and to discharge said cement clinker at a temperature of about350 F.;

b. said cooling means having a pressure zone for cooling said cementclinker from a temperature of about 2.500 F. to a temperature of about1,850 E;

c. a first cooling means adjacent said pressure zone for directing acooling fluid through at a pressure sufficient to pass said coolingfluid through said cooling means and through said bed of said cementclinker to cool said cement clinker from a temperature of about 2,500 F.to a temperature of about l,850 F., and to heat said cooling fluid to atemperature of about 400 to about 500 F. for use as secondary air forsaid burner;

d. said cooling means having a reduction and cooling zone adjacent saidpressure zone for cooling said cement clinker from a temperature ofabout L850 F. to a temperature ofabout l,100 F.;

e. gas generator means in said reduction and cooling zone for directinga reducing fluid having a pressure sufficient to pass said reducingfluid through said cooling means and through said bed to cool saidcement clinker from a temperature of about L850 F. to a temperature ofabout L F. and to exit said reducing fluid from said reduction andcooling zone;

i". said cooling means having a cooling zone adjacent said reduction andcooling zone for cooling said cement clinker from a temperature of aboutL100 F. to a temperature of about 350 F.; and

g. a second cooling means adjacent said cooling zone for directing acooling fluid having a pressure sufficient to pass said cooling fluidthrough said cooling means and through said bed to cool said cementclinker from a temperature of about l,l00- F. to a temperature of about350 F. and to heat said cooling fluid to a temperature of about 230 F.to 250 F. for use as primary air for said burner.

2. The apparatus recited in claim 1 and having a first conducting meansadjacent said discharge end for directing said cement clinker from saiddischarge end to said pressure zone and for directing said heatedcooling fluid from said pressure zone to said discharge end for use assecondary air for said burner.

3. The apparatus recited in claim 1 and having a second conducting meansfor connecting said cooling zone with said burner and for directing saidheated cooling fluid from said cooling zone to said burner as primaryair.

4. The apparatus recited in claim 3 and having blower means in saidsecond conducting means for blowing said heated cooling fluid throughsaid second conducting means.

5. The apparatus recited in claim I wherein said pressure zone isdefined by a pressure compartment on one side of said cooling means.

6. The apparatus recited in claim 5 wherein said pressure zone isdefined by said pressure compartment, a kiln firing hood of said kilnand a first baffle on the other side of said cooling means.

7. The apparatus recited in claim I wherein said reduction and coolingzone is defined by a reduction and cooling compartment on one side ofsaid cooling means.

8. The apparatus recited in claim 7 wherein said reduction and coolingzone is defined by said reduction and cooling compartment, a firstbattle and a second battle on the other side of said cooling means.

9. The apparatus recited in claim 1 wherein said cooling zone is definedby a cooling compartment on one side of said cooling means.

10. The apparatus recited in claim 9 wherein said cooling zone isdefined by a second baifle and an end wall on the other side of saidcooling means.

11. The apparatus recited in claim I wherein said bed has apredetermined depth.

12. The apparatus recited in claim 1 wherein said pressure zone has afirst predetermined length and a retention time of about 6 to about 7minutes.

13. The apparatus recited in claim 1 wherein said reduction and coolingzone has a second predetermined length and a retention time greater than10 minutes.

14. The apparatus recited in claim 1 wherein said cooling zone has athird predetermined length and a retention time of about 20 to about 30minutes.

IS. A method for cooling a cement clinker discharged from a dischargeend of cement kiln and having a burner disposed adjacent said dischargeend, said method including the steps of:

a. receiving a bed of said cement clinker on a grate-type cooling meansfrom said discharge end, the clinker discharging at about 2,700 to 2,800F.;

. cooling said cement clinker in a pressure zone of said coolin meansfrom a temperature of about 2,500 F. to a tempe ature of about L850 F.by directing a cooling fluid at a pressure sufficient to pass saidcooling fluid through said cooling means and through said bed of saidcement clinker to heat said cooling fluid to a temperature of about 400to about 500 F. for use as secondary air for said burner;

. cooling said partially cooled cement clinker in a reduction andcooling zone adjacent said pressure zone of said cooling means from atemperature of about l,850 F. to a temperature of about l,l00 F. bydirecting a reducing fluid having a pressure sufficient to pass saidreducing fluid through said cooling means and through said bed and toexit said reducing fluid from said reduction and cooling zone; and

d. cooling said reduced cement clinker in a cooling zone of said coolingmeans adjacent said reduction and cooling zone from a temperature ofabout L100 F. to a tempera ture of about 350 F. by directing a collingfluid having a pressure suflicient to pass said cooling fluid throughsaid cooling means and through said bed and to heat said cooling fluidto a temperature of about 230 to about 250 F. for use as primary air forsaid burner.

I6. The method recited in claim including the step of conducting saidcement clinker from said discharge end to said pressure zone anddirecting said heated cooling fluid from said pressure zone to saiddischarge end for use as secondary air for said burner.

17. The method recited in claim 15 and including the steps of connectingsaid cooling zone with said burner and directing said heated coolingfluid from said cooling zone to said burner as primary air.

18. The method recited in claim 15 and including the step of blowingsaid heated cooling fluid from said cooling zone to said burner for useas primary air.

19. The apparatus recited in claim I and having a hood connecting saiddischarge end and said pressure zone, a second conducting meansconnecting said cooling zone with said burner, a first pressuke sensingmeans in said hood for sensing the pressure in said hood, a first dampermeans in said second conducting means, and a first control meansconnected to said first damper means and said first pressure sensingmeans for maintaining a slightly negative pressure in said hood.

20. The apparatus recited in claim I and having a third conducting meansconnecting said cooling means and said pressure zone, a second dampermeans in said third conducting means, a first temperature sensing meansin said reduction and cooling zone, and a second control means connectedto said first temperature sensing means and said second damper means tovary the flow of said cooling fluid in said pressure zone and tomaintain said cement clinker at about 1,850 F. as said cement clinkerleaves said pressure zone.

2|. The apparatus recited in claim I and having a fourth conductingmeans between said gas generation means and said reduction and coolingzone, a third damper means in said fourth conducting means, a secondtemperature sensing means in said reduction and cooling zone for sensingthe temperature therein, a third control means connected to said thirddamper means and to said second temperature sensing means to control theflow of reducing fluid through said reduction and cooling zone.

22. The apparatus recited in claim 1 nd having a second pressure sensingmeans in said reduction and cooling zone, exhaust means from saidreduction and cooling zone, a fourth damper means in said exhaust means,and a fourth control means connected to said second pressure sensingmeans and to said fourth damper means to maintain a slightly positivepressure in said reduction and cooling zone.

23. The apparatus recited in claim 1 and having a second exhaust meansconnected to said cooling zone, a fifth damper means in said secondexhaust means, a third pressure sensing means in said cooling zone, anda fifth control means connected to said fifth damper means and to saidthird pressure sensing means to maintain a slightly negative pressure insaid cooling zone.

24. The apparatus recited in claim 1 and having a fifth conducting meansbetween said second cooling means and said cooling zone, and a sixthdamper means in said fifth conducb ing means for controlling the flow ofsaid cooling fluid through said cooling zone.

25. The method recited in claim l5 and including the steps of connectingsaid cooling zone with said burner, sensing the pressure adjacent saiddischarge end of said kiln, damping the primary air to said burner andcontrolling the damping of said primary air to said burner to maintain aslightly negative pressure adjacent said discharge end.

26. The method recited in claim 15 and including the steps of connectingsaid cooling means and said pressure zone, damping the flow of coolingfluid between said cooling means and said pressure zone, sensing thetemperature in said red uction and cooling zone and controlling saiddamping between said cooling means and said pressure zone to maintainsaid cement clinker at about !,850 F. as said cement clinker reachessaid pressure zone.

27. The method recited in claim 15 and including the steps of connectingsaid reduction and cooling zone to a gas generation means, damping theflow of reducing fluid between said reduction and cooling zone and saidgas generation means, sensing the temperature in said reduction andcooling zone. and controlling the damping of said reducing fluid betweensaid reduction and cooling zone, and controlling the damping of saidreducing fluid between said reduction and cooling zone and said gasgeneration means to control the flow of reducing fluid through saidreduction and cooling zone.

28. The method recited in claim l5 and including the steps of sensingthe pressure in said reduction and cooling zone, exhausting saidreducing fluid from said reduction and cooling zone, damping the exhaustof said reducing fluid from said reduction and cooling zone, andcontrolling the damping of said exhaust of said reducing fluid tomaintain a slightly positive pressure in said reduction and coolingzone.

29. The method recited in claim 15 and including the steps of exhaustingsaid cooling zone, damping the exhaust of said cooling zone, sensing thepressure in said cooling zone, and controlling the damping of saidexhaust of said cooling zone to maintain a slightly negative pressure insaid cooling zone.

30. The method recited in claim 15 and including the steps ofconnectingsaid cooling zone to a second cooling means and damping the flow of saidcooling fluid between said cooling zone and said second cooling means tocontrol the flow of said cooling fluid through said cooling zone.

1. Apparatus for cooling cement clinker discharged from a dischargedfrom a discharge end of a cement kiln, said kiln having a burnerdisposed adjacent said discharge end, said apparatus having: a.grate-type cooling means adapted to receive a bed of said cement clinkerfrom said discharge end at a temperature Of about 2,700* to about 2,800*F. and to discharge said cement clinker at a temperature of about 350*F.; b. said cooling means having a pressure zone for cooling said cementclinker from a temperature of about 2,500* F. to a temperature of about1,850* F.; c. a first cooling means adjacent said pressure zone fordirecting a cooling fluid through at a pressure sufficient to pass saidcooling fluid through said cooling means and through said bed of saidcement clinker to cool said cement clinker from a temperature of about2,500* F. to a temperature of about 1,850* F., and to heat said coolingfluid to a temperature of about 400* to about 500* F. for use assecondary air for said burner; d. said cooling means having a reductionand cooling zone adjacent said pressure zone for cooling said cementclinker from a temperature of about 1,850* F. to a temperature of about1,100* F.; e. gas generator means in said reduction and cooling zone fordirecting a reducing fluid having a pressure sufficient to pass saidreducing fluid through said cooling means and through said bed to coolsaid cement clinker from a temperature of about 1,850* F. to atemperature of about 1,100* F. and to exit said reducing fluid from saidreduction and cooling zone; f. said cooling means having a cooling zoneadjacent said reduction and cooling zone for cooling said cement clinkerfrom a temperature of about 1,100* F. to a temperature of about 350* F.;and g. a second cooling means adjacent said cooling zone for directing acooling fluid having a pressure sufficient to pass said cooling fluidthrough said cooling means and through said bed to cool said cementclinker from a temperature of about 1,100* F. to a temperature of about350* F. and to heat said cooling fluid to a temperature of about 230* F.to 250* F. for use as primary air for said burner.
 2. The apparatusrecited in claim 1 and having a first conducting means adjacent saiddischarge end for directing said cement clinker from said discharge endto said pressure zone and for directing said heated cooling fluid fromsaid pressure zone to said discharge end for use as secondary air forsaid burner.
 3. The apparatus recited in claim 1 and having a secondconducting means for connecting said cooling zone with said burner andfor directing said heated cooling fluid from said cooling zone to saidburner as primary air.
 4. The apparatus recited in claim 3 and havingblower means in said second conducting means for blowing said heatedcooling fluid through said second conducting means.
 5. The apparatusrecited in claim 1 wherein said pressure zone is defined by a pressurecompartment on one side of said cooling means.
 6. The apparatus recitedin claim 5 wherein said pressure zone is defined by said pressurecompartment, a kiln firing hood of said kiln and a first baffle on theother side of said cooling means.
 7. The apparatus recited in claim 1wherein said reduction and cooling zone is defined by a reduction andcooling compartment on one side of said cooling means.
 8. The apparatusrecited in claim 7 wherein said reduction and cooling zone is defined bysaid reduction and cooling compartment, a first baffle and a secondbaffle on the other side of said cooling means.
 9. The apparatus recitedin claim 1 wherein said cooling zone is defined by a cooling compartmenton one side of said cooling means.
 10. The apparatus recited in claim 9wherein said cooling zone is defined by a second baffle and an end wallon the other side of said cooling means.
 11. The apparatus recited inclaim 1 wherein said bed has a predetermined depth.
 12. The apparatusrecited in claim 1 wherein said pressure zone has a first predeterminedlength and a retention time of about 6 to about 7 minutes.
 13. Theapparatus recited in claim 1 wherein said reduction and cooling zone hasa second predetermined length and a retention time greater than 10minutes.
 14. The apparatus recited in claim 1 wherein said cooling zonehas a third predetermined length and a retention time of about 20 toabout 30 minutes.
 15. A method for cooling a cement clinker dischargedfrom a discharge end of cement kiln and having a burner disposedadjacent said discharge end, said method including the steps of: a.receiving a bed of said cement clinker on a grate-type cooling meansfrom said discharge end, the clinker discharging at about 2,700* to2,800* F.; b. cooling said cement clinker in a pressure zone of saidcooling means from a temperature of about 2,500* F. to a temperature ofabout 1,850* F. by directing a cooling fluid at a pressure sufficient topass said cooling fluid through said cooling means and through said bedof said cement clinker to heat said cooling fluid to a temperature ofabout 400* to about 500* F. for use as secondary air for said burner; c.cooling said partially cooled cement clinker in a reduction and coolingzone adjacent said pressure zone of said cooling means from atemperature of about 1,850* F. to a temperature of about 1,100* F. bydirecting a reducing fluid having a pressure sufficient to pass saidreducing fluid through said cooling means and through said bed and toexit said reducing fluid from said reduction and cooling zone; and d.cooling said reduced cement clinker in a cooling zone of said coolingmeans adjacent said reduction and cooling zone from a temperature ofabout 1,100* F. to a temperature of about 350* F. by directing a collingfluid having a pressure sufficient to pass said cooling fluid throughsaid cooling means and through said bed and to heat said cooling fluidto a temperature of about 230* to about 250* F. for use as primary airfor said burner.
 16. The method recited in claim 15 including the stepof conducting said cement clinker from said discharge end to saidpressure zone and directing said heated cooling fluid from said pressurezone to said discharge end for use as secondary air for said burner. 17.The method recited in claim 15 and including the steps of connectingsaid cooling zone with said burner and directing said heated coolingfluid from said cooling zone to said burner as primary air.
 18. Themethod recited in claim 15 and including the step of blowing said heatedcooling fluid from said cooling zone to said burner for use as primaryair.
 19. The apparatus recited in claim 1 and having a hood connectingsaid discharge end and said pressure zone, a second conducting meansconnecting said cooling zone with said burner, a first pressure sensingmeans in said hood for sensing the pressure in said hood, a first dampermeans in said second conducting means, and a first control meansconnected to said first damper means and said first pressure sensingmeans for maintaining a slightly negative pressure in said hood.
 20. Theapparatus recited in claim 1 and having a third conducting meansconnecting said cooling means and said pressure zone, a second dampermeans in said third conducting means, a first temperature sensing meansin said reduction and cooling zone, and a second control means connectedto said first temperature sensing means and said second damper means tovary the flow of said cooling fluid in said pressure zone and tomaintain said cement clinker at about 1,850* F. as said cement clinkerleaves said pressure zone.
 21. The apparatus recited in claim 1 andhaving a fourth conducting means between said gas generation means andsaid reduction and cooling zone, a third damper means in said fourthconducting means, a second temperature sensing means in said reductionand coOling zone for sensing the temperature therein, a third controlmeans connected to said third damper means and to said secondtemperature sensing means to control the flow of reducing fluid throughsaid reduction and cooling zone.
 22. The apparatus recited in claim 1 ndhaving a second pressure sensing means in said reduction and coolingzone, exhaust means from said reduction and cooling zone, a fourthdamper means in said exhaust means, and a fourth control means connectedto said second pressure sensing means and to said fourth damper means tomaintain a slightly positive pressure in said reduction and coolingzone.
 23. The apparatus recited in claim 1 and having a second exhaustmeans connected to said cooling zone, a fifth damper means in saidsecond exhaust means, a third pressure sensing means in said coolingzone, and a fifth control means connected to said fifth damper means andto said third pressure sensing means to maintain a slightly negativepressure in said cooling zone.
 24. The apparatus recited in claim 1 andhaving a fifth conducting means between said second cooling means andsaid cooling zone, and a sixth damper means in said fifth conductingmeans for controlling the flow of said cooling fluid through saidcooling zone.
 25. The method recited in claim 15 and including the stepsof connecting said cooling zone with said burner, sensing the pressureadjacent said discharge end of said kiln, damping the primary air tosaid burner and controlling the damping of said primary air to saidburner to maintain a slightly negative pressure adjacent said dischargeend.
 26. The method recited in claim 15 and including the steps ofconnecting said cooling means and said pressure zone, damping the flowof cooling fluid between said cooling means and said pressure zone,sensing the temperature in said reduction and cooling zone andcontrolling said damping between said cooling means and said pressurezone to maintain said cement clinker at about -,850* F. as said cementclinker reaches said pressure zone.
 27. The method recited in claim 15and including the steps of connecting said reduction and cooling zone toa gas generation means, damping the flow of reducing fluid between saidreduction and cooling zone and said gas generation means, sensing thetemperature in said reduction and cooling zone. and controlling thedamping of said reducing fluid between said reduction and cooling zone,and controlling the damping of said reducing fluid between saidreduction and cooling zone and said gas generation means to control theflow of reducing fluid through said reduction and cooling zone.
 28. Themethod recited in claim 15 and including the steps of sensing thepressure in said reduction and cooling zone, exhausting said reducingfluid from said reduction and cooling zone, damping the exhaust of saidreducing fluid from said reduction and cooling zone, and controlling thedamping of said exhaust of said reducing fluid to maintain a slightlypositive pressure in said reduction and cooling zone.
 29. The methodrecited in claim 15 and including the steps of exhausting said coolingzone, damping the exhaust of said cooling zone, sensing the pressure insaid cooling zone, and controlling the damping of said exhaust of saidcooling zone to maintain a slightly negative pressure in said coolingzone.
 30. The method recited in claim 15 and including the steps ofconnecting said cooling zone to a second cooling means and damping theflow of said cooling fluid between said cooling zone and said secondcooling means to control the flow of said cooling fluid through saidcooling zone.